A DOCTOR at Byron District Hospital was paid more than $440,000 in overtime over three years due to a dangerous shortage of medical officers.

The NSW Auditor-General's latest report revealed the doctor earned $158,818 in overtime last financial year, bringing the total to $442,534 above the normal wage since 2012-13.

Northern NSW Local Health District CEO Chris Crawford said the doctor worked 12-hour shifts, with only 10 hours paid at the normal rate.

"It is more cost effective to pay this medical officer on the above basis than to employ a locum medical officer," he said.

"(A locum doctor) would receive a higher pay rate for every hour worked, as well as payment of transport and accommodation expenses that are necessary to facilitate the locum medical officer travelling to and staying in Byron Bay."

The real problem is that there are just not enough doctors to go around.

And those who are available do not want to work at smaller regional hospitals without being duly compensated.

Mr Crawford said the hospital had made many attempts to employ another career medical officer at standard rates, but had repeatedly failed to find anyone willing.

He said the exorbitant overtime outlay should become a thing of the past once the area's new hospital was up and running.

"When the Byron Central Hospital replaces Byron District Hospital in about three to four months' time, this amount of medical officer overtime will be eliminated," he said.

"Instead of 12-hour shifts, medical officers will either work eight or 10-hour shifts.

"Also, as the Byron Central Hospital (replacing Byron and Mullumbimby District Hospitals) is a bigger hospital, it will be better positioned to recruit permanent career medical officers to staff these eight and 10-hour shifts."

The state-wide audit revealed Byron District Hospital employed one of only four doctors who were paid more than $120,000 in overtime last year.

"Overtime is paid at a premium rate and, if not effectively managed, can result in higher costs and work, health and safety issues, particularly when fatigued employees perform high-risk tasks," the report stated.

A Bureau of Health report this month revealed emergency department waiting times had blown out across the state.

About 39% of emergency patients in Lismore waited longer than four hours in the July-September quarter, while in Coffs Harbour and Grafton the figure was 27%.

The latest audit showed ambulance response times had stretched from 10.8 minutes in 2013-14 to 11.2 minutes last fiscal year.